Cutting tools such as the cutting tool described in Japanese Unexamined Patent Application Publication No. 2007-519532A (Patent Document 1) have been known as cutting tools used for machining work materials such as metals. The cutting tool described in Patent Document 1 is provided with a cutting insert and a base (holder) to which the cutting insert is attached. The positioning of the cutting insert with respect to the holder is likely to become unstable when a surface where the cutting insert comes in contact with the holder is a flat surface. For example, when fixing a cutting insert to a holder by a screw, it is necessary to provide a ‘looseness’ in the screw hole in order to insert the screw in a stable manner. Therefore, the positioning of the cutting insert becomes unstable by an amount relative to the amount of this looseness.
In view of this, the surface where the cutting insert comes in contact with the holder in Patent Document 1 has a wave-type shape and includes a plurality of projecting portions that are mutually separated by a plurality of grooves. The accuracy of positioning of the cutting insert with respect to the holder is increased because this type of wave-type contact surface is provided.
However, when the surface where the cutting insert comes into contact with the holder is the wave-type surface described in Patent Document 1, because of the problems involved in manufacturing accuracy, the wave-type contact surface of the cutting insert may not mate closely with the wave-type contact surface of the holder. Therefore, depending on the manufacturing accuracy, the cutting insert may contact with the holder only at two points, and this makes it difficult to fix the cutting insert to the holder in a stable manner.
In addition, in order to fix the cutting insert to the holder in a stable manner, sometimes a side surface adjacent to the above-mentioned contact surface of a cutting insert is made to be in contact with the holder. In this case, because of the wave-type contacting surfaces of the cutting insert and the holder not mating with each other, the cutting insert gets shifted from the desired position, and it may become difficult to make the side surface be in contact with the holder.
The present embodiment is made in view of the above-mentioned problems, and provides a cutting tool that can fix a cutting insert to a holder in a stable manner.